1808 Inorganic Chemistry, Vol. 10, No. 8, 1971
wherein the selenocyanates are noncoordinated, emphasizing the effects of the steric hindrance due to the ethyl groups of the Et4dien in determining the overall geometry of the complexes. As can be seen from Table I, all of the Cu”-Et4dien and -dien complexes generally function as 1: 1 electrolytes in acetonitrile. The [Cu(dien)NCO][B(CeH6)4]. CHIOH complex retains the methanol molecule even on pumping under vacuum for several days, in contrast to [Ni(Etrdien)NCO][B(CGH5)4]. CH30H, indicating that the methanol is probably coordinated to the copper(I1). The Y C doublet ~ in the solid-state infrared spectrum (Table 11) of [Cu(Etadien)NCO][B(C6HS)4] must be due to different crystal environments, since the extra band does not appear in the solution spectrum. Heating the solid compound a t
RICHARD E. DESIMONE AND GALEND. STUCKY 40’ for 2 weeks did not change the spectrum, indicating that linkage isomerism is most likely not involved. The visible spectra of these complexes (Table 111) are typical of copper(I1) complexes, consisting of broad bands which are, in some cases, resolved into a doublet. Other complexes whose preparations were attempted included [Cu(dien)NCO INCO, [ Cu(dien) Cl] [B(C6H5)4], [ Cu (dien)NCS ] [B(CtiHb)4 1 , and [Cu(Et4dien)NCOINCO. In all cases a product was isolated and the infrared spectrum exhibited the appropriate absorption bands, but the analyses were unsatisfactory.
Acknowledgments.-The authors wish to express their sincere appreciation to the National Science Foundation (Grant No. GP-8327) for the support of this research.
CONTRIBUTION FROM THE WILLIAM8 . NOYESLABORATORY, SCHOOL OF CHEMICAL SCIENCES, DEPARTMENT O F CHERIISTRY, UNIVERSITY O F ILLINOIS, URBANA, I L L I N O I S 61801
The Crystal and Molecular Structure of 4-Methylpyridinium Triphenylphosphine Tribromozincate BY RICHARD E. DESIMONE A N D GALEN D. STUCKY*
Received September 20, 1970 The structure of 4-methylpyridinium triphenylphosphine tribromozincate, [ ~ - C H ~ C Z H ~[ZnBr3((CeH6)3P)], NH] has been determined from three-dimensional X-ray data collected by counter methods. The structure has been refined to a final unweighted R factor of 0.063 and a weighted R factor of 0.074 for 1533 independent nonzero reflections. The compound crystallizes in the space group Csh5-P21/c of t$e monoclinic system containing four molecules per unit cell of dimensions a = 10.021 (12), b = 9.827 (15), c = 26.674 (40) A, and (3 = 101.30 (7)’. The measured and calculated densities are 1.706 i 0.015 and 1.700 g/cm3, respectively. The coordination geometry about the zinc atom is a distorted tetrahedron with one bromine atom strongly hydrogen bonded to the N-H proton of the 4-methylpyridinium cation, resulting in significant deviation from the expected Cavsymmetry. Phenyl groups pf the triphenylphosphine molecule were refined as rigid groups with angles of 120’ and carbon-carbon distances of 1.392 A. Coordination geometry about the phosphorus atom is that of a slightly elongated tetrahedron. The distortion of the 4-methylpyridinium cation due to the hydrogen-bonding interaction with the bromine atom appears to be less than can be determined from the data.
With the intention of studying the magnetic properties of transition metal ions tiith fourfold coordination and Cawsymmetry, we have determined the crystal and molecular structure of 4-methylpyridinium triphenylphosphine tribromozincate, which could serve as a diamagnetic host lattice for other divalent paramagnetic ions. In this connection, the effect of lattice-anion interactions as well as the details of the anion geometry were of interest. In addition, we note that there is little structural data on four-coordination conlplexes of ~inc(II).l-~ Experimental Section 4-Methylpyridinium bromide was prepared by bubbling HBr through a solution of previously distilled 4-methylpyridine in diethyl ether. The white, hygroscopic product which immediately formed was filtered and washed under N P with dry ether. [4-CH3GHaNH][ZnBrs(CsHj)3P] was prepared by combining R . S. Sagerand W. H. Watson, Inovg. Chem., 7, 1358 (1968). C. W. Riemann, S. Block, and A. Perloff, ibid., 5 , 1185 (1966). T. Ikeda and H. Hagihara, Acta Crystallogv., 21, 611 (1966) (a) B. Morosin and E. C. Lingafelter, ibid., 12, 611 (1959); (b) N.S . Gill and R . S. Nyholm, J . Chem. SOC., 3997 (1959); ( c ) P. Pauling, Ipzovg. Chewz., 6, 1498 (1960). (1) (2) (3) (4)
ethanol solutions, each containing 0.01 mol of triphenylphosphine, 4-methylpyridinium bromide, and anhydrous zinc bromide. The resulting solution was boiled for about 5 min to ensure complete reaction and was then filtered. Upon cooling, crystals of the desired complex precipitated in good yield. These were washed with ethanol and ether and dried in DUCUO. Anal. Calcd for C ~ A H ~ ~ B ~ C, ~ S43.58; P Z ~ H, : 3.50; Br, 36.24; Zn, 9.88. Found: C, 43.85; H,3.49; Br, 36.29; Zn, 9.87. Wellformed crystals were grown from ethanol-acetonitrile mixtures by slow evaporation under vacuum. The compound exhibited three crystal habits depending on the composition of the solution from which crystals were grown. X-Ray investigation showed all forms to be crystallographically equivalent.
Collection and Reduction of Intensity Data Optical investigation immediately showed the crystals to be biaxial. Precession photographs of the hkO, h k l , Okl, and l k l reciprocal lattice nets using 310 KE radiation (A 0.71069 f i ) indicated a monoclinic space group. The systematic absences, 1 = 2n for h01 and k = 2n for OK0 uniquely determined the space group t o be C2&P21/C.j For collection of intensity data, a small crystal approximating a hexagonal cylinder of dimensions -0.3 (5) “International Tables for X-Ray Crystallography,” Vol. I , Kynoch Press, Birmingham, England, 1962, p 99.
Inorganic Chemistry, Vol. 10, No. 8, 1971 1809 mm in height and 0.25 mm in diameter was mounted in a 0.3-mm glass capillaryand aligned on a Picker four-circle automatic diffractometer with the a* axis roughly aloqg the spindle axis. Lattice constants ( 2 2 O , X 0.71069 A, Mo K n ) and standard deviations obtained by leastsquares refinement6 of the angular settings of 12 moderately intense hand-centered reflections were odetermined to be p = 10.021 (12) A, b = 9.827 (15) A, c = 26.674 (40) A, and /3 = 101.30 (7)O, giving a unit cell volume of 2585.7 A3. The density calculated for 4 molecules/unit cell is 1.700 g/cm3 and agrees well with the measured density of 1.706 + 0.015 g/cm3 measured by flotation in a chloroform-bromoform mixture. Intensities were measured with a scintillation counter mounted 29 cm from the crystal which was positioned 21 cm from the source. The diffractometer was equipped with a highly oriented graphite single-crystal monochromator and the detector aperture was 4 mm X 4 mm; no attenuation of the diffracted beam was found to be necessary. Data were collected using the 8-28 scan technique to 50" in 28 with a scan width of 1.50" and a takeoff angle of 0.94". Stationary background counts of 10-sec duration were taken a t the beginning and end of the scan, One form (hkl and hkl) was measured giving a total of 4675 reflections. The small number of symmetry-related reflections collected was averaged. Intensities were corrected for Lorentz polarization' and absorption8 ( p = 59.8 cm-l; transmission factors varied from 0.20 to 0.28). Reflections were considered to be observed if I o 5 3u(10), The resulting set of 1533 unique observed reflections was used in the subsequent refinement. Scattering factors for nonhydrogen atoms were taken from the compilation of Hanson, et u L . ~ Hydrogen scattering factors were those of Stewart, et al.,1° and anomalous dispersion corrections (Af' and Af") for Zn and Br were taken from the compilation of Cromer .l1 ~
Solution and Refinement of the Structure The structure was refined by full-matrix least-squares and Fourier techniques. l 2 A three-dimensional Patterson function revealed the positions of the zinc and bromine atoms. The phosphorus atom was located by a subsequent Fourier synthesis. A structure factor calculation including the three bromine, the zinc, and the phosphorus atoms resulted in an unweighted R factor RI = ZI/Fol - l F c ~ l / Z F o= 0.244 and a weighted R factor Rz = ( Z w ( F o - F o ) z / Z ~ F o z ) ' /=z 0.302. A Fourier synthesis based on this calculation revealed the nitrogen atom and all 24 carbon atoms. The phenyl groups, with hydrogen atoms, were included as rigid bodies giving R1 = 0.155 and Rz = 0.165. Two cycles ( 6 ) W. R. Busing and H. A. Levy, Acta Cvyslallogr., 22, 457 (1967). (7) T. J. Kistenmacher, Ph.D. Thesis, University of Illinois, 1970, p 72. (8) ORABS-11,a local modification of the program ORABS by D. J. Wehe, W. R. Busing, and H. A. Levy. (9) H. P. Hanson, F. Herman, J. 0. Lea, and S. Skillman, Ac2a Cvystallogv., 17, 1040 (1864). (IO) K. F. Stewart, E. R. Davidson, and W. T. Simpson, J . Chem. Phys., 42, 3175 (1865). (11) D. T. Cromer, Acta Crystallog?., 17, 1040 (1964). (12) Local versions of several standard computer programs were used. Fourier syntheses were carried out with J. Gvildey's "Two- and ThreeDimensional Fourier Summation Program." The least-squares program was W. R. Busing, K. 0. Martin, and H. A. Levy's ORBLS. Interatomic distances and angles and their standard deviations were calculated by Busing, Martin, a n d Levy's ORFFE. K. Johnson's ORTEP was used to draw the structural illustrations.
c.
of least-squares refinement on the scale factor, group, and positional parameters reduced RI to 0.102 and Rz to 0.110. Two further cycles of refinement including isotropic thermal parameters reduced R1 to 0.112 and Rzto 0.089. Introduction of anisotropic thermal parameters for zinc, bromine, and phosphorus along with the anomalous dispersion correction reduced R1 to 0.079 and R2 to 0.072. At this point, it was found that the values of w ( F o - Fc) displayed a strong systematic variation with both (sin 8)/X and the magnitude of F,, indicating that the counting statistics weighting scheme was unsatisfactory. Assignment of equal weights to all reflections eliminated this difficulty and it was decided to continue with this weighting since no other weighting scheme seemed justifiable. Two cycles of least-squares refinement based on "unit weights" with a total of 110 parameters yielded RI = 0 065 and Rz = 0.076. The N-H proton of the cation ?as located from a difference Fourier map and the ring protons of the cation were put in their "calculated positions" 1.0 d from their respective carbon atoms. In an attempt to improve the reliability of the cation ring parameters, anisotropic thermal parameters were assigned to the nitrogen atom and t o the six carbon atoms of the cation. Two cycles of least-squares refinement of the 63 cation parameters (hydrogen parameters were not varied) and the scale factor resulted in final values of RI 7 0.063 and Rz = 0.074. No peaks larger than 0.5 e-/A3 were observed in the final difference Fourier map. The final positional group and thermal parameters are tabulated in Tables I and 11. A partial listing of bond lengths and angles and their errors appears in Table 111. The observed and calculated structure factors for the observed reflections are given in Table IV. Figure 1 shows the coordination sphere about the zinc atom,
Figure 1. Inner coordination sphere about the zinc atom. Thermal ellipsoids are drawn to encompass 50% probability.
Figure 2 the anion, Figure 3 the entire molecule looking approximately down the zinc-phosphorus bond, and Figure 4 is a projection of the contents of the unit cell onto the ac plane. Description of the Structure Anion Geometry.-One of the assumptions made before the determination of this structure was that the anion would approximate closely enough to symmetry that the spectral and magnetic properties could be interpreted on the basis of an axial model. The
1810 Inorgunic Chemistry, Vol. 10, N o . 8, 1971
Atom
X
Br(1) 0.0430 ( 5 ) Br(2) 0.4354 (6) Br(3) 0.2968 (7) Zn 0.2659 (6) P 0.3386 (12) N 0.682(6) C(19) 0.799 (8) C(20) 0.920 (5) C(21) 0.921 (6) C(22) 0.801 (6) C(23) 0.675 (6) C(24) 1.059 (5) H(1@) 0,587 H(17C) 0.798 H ( l s c ) 1.007 H ( l g C ) 0.586 H(20") 0.800
RICHARD E. DESIMONE AND GALEND. STUCKY
TABLE I POSITIONAL, THERMAL, AND GpoUp PARAMETERS FOR Y z Bllb Pia 0.0888 (6) 0.1142 (2) 0.0100 (7) 0.0125 (8) 0.0091 (6) 0.1526 (2) Q.0115(7) 0.0103 (7) 0.2851 (7) 0.2263 ( 2 ) 0.0204 (11) 0.0190 (11) 0.1693 (6) 0.1469 (2) 0.0112 (8) 0.0100 (8) 0.3273 (13) 0.0869 ( 5 ) 0.0077 (15) 0.0072 (16) 0.139 (5) 0.229 (2) 0.026 (10) 0.014 (7) 0.117(7) 0.215 (3) 0.024 (12) 0.019 (11) 0.155 (7) 0.245 (2) 0.008 (7) 0.017 (9) 0.224 (5) 0.290 (2) 0.016 (8) 0.006 (6) 0.247 (6) 0.302 (2) 0.014 (8) 0.016(9) 0.204 (8) 0.271 (3) 0.011 (9) 0.029 (14) 0.268(6) 0.321 (2) 0.009 (7) 0.018 (9) 0.107 0.230 7.0d 0.072 0,181 7.0d 0.131 0,235 7.0d 0.226 0.283 7.0d 0.297 0.335 7.0d
[ZnBra((Cf,He)rP)][4-CH3CjHaNHIa Pa3
Be
Group
013
PI2
0.0030 (1) 0.0024 (1) 0.0020 (1) 0.0016 (1) 0.0013 (2) 0.001 (1) 0.003 (2) 0.002 (1) 0.002 (1) 0.002 (1) 0.003 (2) 0.003 (1)
-0.0021 (7) 0.0001 (7) -0.0044 (9) -0.0010 (7) -0.0006 (13) 0.000 (6) 0.004 (10) 0.002 (7) 0 , 0 0 2 (6) 0.007 (7) 0.004 (9) -0.002 (7)
Pf
0.0012 (3) 0.0002 (2) 0.0029 (3) 0.0013 (2) 0.0009 (5) -0.000 (2)
0.005(4) 0.001 (2) 0.002(2) 0.002 (2) 0.001(3) 0.000 (2)
ef
028
0,0002(3) 0 0000 (3) -0.0018 (3) 0,0002( 3 ) 0,0002(3) 0,001 (2) -0.002 (3) 0.001 (3) -0.001 ( 2 ) -0.001 (2) 0 , 0 0 6 (4) -0.002 (3)
9J
Ring 1 0.5192 ( 2 5 ) 0.3660 (23) 0,1091 (10) 0.0 3.790 (32) -0.881 (21) 3.863 (32) Ring 2 0.2451 (24) 0.4831 (27) 0.0758 (9) 0.0 2.912 (22) -0.078 (22) - 1.043 (22) Ring 3 0.3290 (20) 0.2503 (27) 0,0234 (10) 0.0 1.808(22) 0.385 (22) 2.839 (24) a Kumbers in parentheses are estimated uncertainties in last decimal places. b The form of the anisotropic ellipsoid is exp[ - (pllh2 Positional and thermal parameters of the hydrogen atoms were not refined. d Hydrogen &k2 P 3 d 2 4- puhk P13hZ Psakl)]. atoms were given isotroDic temoerature factors of the form exp[-B(sin* 6 ) / k a ] which were set numerically equal to 7.0. e Group B set equal to zero. Atomic B's varied in refinement f Inradians.
+
a
+
+
+
TABLE I1 PARAMETERS OF GROUPATOMS X Y z Ea 0 5193 0 3660 0,1092 3r72 (114) 0 6196 0,0839 0 3199 5 . 6 1 (133) 0 5930 0.0504 0 2678 7.0 (. . .) 0 7561 0,1044 0 3449 5 . 5 7 (137) 0 8296 0 3111 0,0858 7.0(..,) 0 7924 0 4160 0.1501 5 . 7 5 (145) 0 8924 0 4343 0,1651 7 . 0 ( .. . ) 0 6921 0 4621 0.1754 5.46 (141) 0 7186 0 5142 0.2090 7.0 (. . .) 0 5555 0 4371 0,1550 4.66 (132) 0 4820 0 4709 0,1735 7.0(.. .) 0 2452 0 4833 0,0758 3 . 6 2 (111) 0 3086 0 6038 0.0662 6 . 0 7 (153) 0 4111 0 6058 0.0679 7,0(.,,) 0 2320 0 7217 0,0541 7.62 (179) 0 2784 0.0470 0 8100 7.0 (. . .) 0 0920 0 7190 0,0516 5 . 9 8 (153) 0 0359 0,0428 0 8054 7.0(. . .) 0 0286 0 5985 0,0613 5 . 5 5 (138) -0 0739 0 5965 0.0595 7.0 i . . . ) 0 1052 0 4806 0.0734 5.22(130) 0 0588 0,0804 0 3923 7.0(.. .) 0 3290 0,0234 0 2504 3 . 5 3 1113) 0 3003 0 1123 0,0167 6 . 2 1 (i59j 0 2858 0 0545 0.0470 7.0 ( . . . ) 0 2914 0 0530 -0.0312 7 . 8 8 (191) 0 2704 -0 0482 -0.0361 7 . 0 (.'. . ) 0 3111 0 1319 -0.0725 7.34 (180) 0 3047 0 0884 -0.1076 7.0 (. . . ) 0 3399 0 2700 - 0,0658 5.44 (140) 0 3543 0 3278 -0.0960 7 . 0 ( .. . ) 0 3488 0 3292 -0.0179 5.17 (131) 0 3698 0 4305 - 0.0130 7 . 0 ( . . . ) Isotropic temperature factor of the form exp[-B(sin2 6)/
TABLE I11 SELECTED BONDLENGTHS(A) A N D ANGLES( D E G ) ~ 369 (9) Br(1)-Zn-Br(3) 115 9 (3) 411 (14) Br(1)-Zn-P 110 5 ( 4 ) 371 (10) Br(l)-Zn-Br(2) 112 3 (3) 425(9) Br(3)-Zn-P 106 9 (4) Br(B)-Zn-Br(2) 108 9 (4) Br (2)-Zn-P 101 2 (4) P-C(1) 1 84 (3) C(13)-P-C(7) 104 7(12) P-C(7) 1 83 (3) C(13)-P-C(1) 105 O ( 1 2 ) P-C(13) 1 82 (3) C(13)-P-Zn 114 l ( l 1 ) 106 9 ( 1 2 ) C (7)-P-C (1) C(7)-P-Zn 115 7(10) C ( 1)-P-Zn 109 7 (9) C(19)-N 1 32 (7) C(19)-N-C(23) 121 7 (50) C(20)-C(19) 1 37 (7) C(20)-C(19)-K 121 l ( 5 0 ) C(21)-C(2O)-C(19) 120 5 (50) C(21)-C(20) 1 36 (7) C(22)-C(21) 1 33 (7) C(22)-C(2l)-C(20) 116 5 (50) C(23)-C(22) 1 42 (7) C(21)-C(22)-C(23) 123 5 (50) C(22)-C(22)-C(23) 123 5 (50) C(24)-C(21) 1 54 (7) 119 9 (50) 1 32 (7) Av ring C(23)-N 3 22 iX-H(16)-Br(2) 120 5 N-Br(2) 1 01 C(21)-S-Br(2) 169 2 N-H(16) H(16)-Br(2) 2 57 C(21)-X-H(16) 142 5 5 Errors in lattice parameters are included in the estimated ,tandard deviations
Zn-Br(1) Zn-Br(2) Zn-Br(3) Zn-P
2 2 2 2
h21.
Zn-Br distances in two ,Of the bonds are -2.37 A while the third is -2.41 A, a considerable and significant elongation due, i t appears, to a strong hydrogenbonding interaction with the cation.13 Angles around the zinc atom range from -101 2 t o -115.9" but are within the range noted by Taylor, et al.,14in Ni((C6(13) F K Ross and G D Stuck?, J Amev Chem Sac 92, 4538 (1970) (14) R P Tayloi, D. H Templeton, A Zaikln, a n d W D Horrocks, Inorg Chem 7 , 2 6 2 9 (1968)
Figure 2.-Structure
of the anion ZnBr3(Cd%)J'-
[4-CH3C6H4NH I [ZnBr3((C6H&P)1
Inorganic Chemistry, Vol. 10, No. 8, 1971 1811
TABLE IV OBSERVED AND CALCULATED STRUCTURE FACTORS IN ELECTRONS ( X 10) FOR [4-CHaCaH*NH][Zr~Bra(P(CeHa)~)l K
H
085
CAL
n -4
K 7
OBI 59"
CAL iB,
H
00s
- 44
+no 571
339 326
-4
1,,3
-5
I
i
"79 118 7011 U2L
-j
1
L
6
- 6b 7
279 1113 431 672
351 974
946
7
474
-- 66
369
K
085 CAL i 1507 1137 1 200 67 2 462 436 2 I l l 5 1072 3 507 1 3 5 3 29,> 178
-2
2 -2
2
-2
2 -7.
4 1384 1354 4 h79 6%
-2
5 1539 1557 h 617 599 6 348 415 7 455 410 R 4f.7 '139 H 3 ~ 9 3113 1 1204 1246 7. 7 5 6 168
2
Sll
5
-3 -5 -3
1L
579 240
77" k31 431 %74 2 5 4 4no 46n 31 6 P b 4
-I
t I
H 2
CIL 42t
-7. -7.
2 -2 -3 3
-" 8 -fl
-4 -9 -9
-10 -11 -10
0 0
1
I 2 6 6 241
d3
-ti 4
-1
-1 1 -1 'I I
1
-3
-11
-L9P r .
-5
1
h
-2 -22
0
"
LIh
- 22
1
463
431
706
1
si,n
686
-1
- 1!
7h
7
7 i i 2
h
-6 -h
1
441
6
,
465
,6
-1
I
461 537
-5
4 4
373 *ii 5132 ?on 711 349
391 39n 520
w8
733 382
1 ! i
604
bjl
6
7R5 556
7 -7 7
21"
-9
,
- 22 -2
2
*//
960 Cli 141 514
>,
- z2 -2
/j
7 2 4
0 c -2
2
1
51% Y77
-2 2 -7. 2 -2 2 -2 2 -33
-33 -3 3 -3
-3
-3 3
-3
4
-4 4 -4 4 -4
4
-4 -4 5 -55
-5 -5
$ -6
6 -6
h
-6 -7 7 -7 'I -7'I -7P (I
-8 -1, -K
-h 9
2
3 -3 3 414 6 9 1 3 t, 9 3 0 ~ 7 0 -3 5 2ss 995 -3 3 1 I75 355 -3 2 141 520 -33
8
9
6 5
-IO
326 320
155
273
WPIIIXIL. IIUIIU~LI 0 1 1 5 6 5 1403
65R
0
628
0 U
451 352
0
3 941 4 739 5 240 6 638
935 69'1
2h4
-3 4 -4 4
-4
4 -4 4
656
-4
-S 5
-5
1
-2 - 22
-2
2hR
3
-1 1 '1 1 -1
- 27.
342
7 -32
-1
-12
X
911 556 186 262
7
H
414 338
2 - 22
11
2 -22
-33
-1 1 -1 -I1
- 1 1' , )1
-22
462
997 >,:l i 7 6 3"l 1133 2"7 227 6+4 *OR
2!0
1H4 0 5 2 1379 2'36 2 6 5 501 *US 577. >17 410 435 471 449 369 3R9 719 7 2 1 7 1 s 740 -7 h i'bl 931 *PO 510 w n 3 7 ~ -8 5 764 h14 5U3 6'7 015 7iR 21" 114
*,*
3x6
446 347 'rli 640
-7 7
1
3 -3 3 -33
3
343 7117
1 5h3
-1 2
0
01s C I L 1 13114 1446 %,I) 249 2 l(13h 9111 1
!
-6
I
x
n
0
7 7
-4
3
-3 3
0
-6
-6
I(
->
h -6 6
lis:
0
644
CAL
OBI
-A h
6
-7 --,: 7
x
R -8 -8 8 .-R '8
2 1
n.
H
-7
-5
5
-5
5
-5
5
-5
5 -5
-5 -5 6 -6 -6 h -6 -A
-6 6 -h 7 -7 7 -7 7
"1
322
1
256
2
101
2
5Ls
3 L 5
671 7113 493
i i l ,
547
607 2'17 291
9
w3
377 323
1 -1 1 -1 1 1 '1 -1 1 -1
2 -2 2 -Z 2 2 -2 -2 2 -2
3 3 -3
3
1.
4 h
6
365
386
7
307 402 336 457 106s HlZ M5 343
335 4++
'I 9
2 3 3 5
s
-3
7
-ir
'r
-4 4
-4 4 -4
-4 r'
4
-4
-5 S -5 5 6 -6 -6 -6 -1
748 380 bll 329
1 576 1 920 2 340 2'lZ 2 661 6 5 5 4 422 6 3 3 5 733 7 4 3 5 278 2 3 5 h 3 8 6 337 R 636 635 111 352 346 1 646 690 I 1001 1041 2 690 705 2 874 6 4 9 3 4 1 3 869 8 BRO 368
-3
-3 3 4
10~2
" 9
1
530
447 519
low
I. 1228 2 285 2 2Rl 3 3hh 3 489 4 479 4 669 6 290 7 296 8 370 9 320 2
5x0
270
395
iwo 790
544 384 5*R 683 522 Inn1 1196 306 211 374 513 496 633 210 217 610 307 5 s
415 442 1076 io90 464 4 5 0 399 404 1 959 9 8 1 2 3 h 3 334 4 503 513 f 304 415 -7 I 749 780 -7 6 312 105 -7 7 337 320 -R 2 41R 425 -8 3 563 494 -8 I 482 4nz -9 4 409 391 -9 5 319 229 -10 3 471 461 s#**4~**L=l%*>
516 528
517
625
507 -3
276
26,
286
305 288
247
*29
'75
353
345 625 173 LO4 714 392 B12
boa
793
381
641 438 3"6 396 358
379
426
313 387
366
332
251
b8
303 355
296 252
-*
190
5
L
**+
2
-2 -3 -3
-3
2
re3
4 7
361 321
3 3
301
O'L 385
475
419
263 348 333 167
mI'
3
413
&
2*3
313
-+
314 375
22L
2
-5
3
353
3'2
-7
1
311t
355
d
-1 2 328 .IUY*,L.24**U** 0 0 bo0 1 1 465
3011 164
637 'I85
-1
3
382
2
0
363
339 332
-2 - 32
0 ?0
327 146 521
L* 1965
4
0
-4 5 -5
I 0
388 375
189
-6
-7
350
3&6
378
279
2
'118
43,
b
3L9
311
504
+P?
o
Y's*ri*L:26*r*rr
0
-1
0 0
652 319
*5L 384
pitch of the phenyl rings also noted by Taylor, et al., appears t o be different than in Ni((C;H6)3P)Ia- and presumably reflects the difference in the cation and in the crystal packing.
1812 Inorgunic Chemistry, Val. 10, N o . 8 , 1971
Figure 3 .-Structure
of the molecule looking approximately along the zinc-phosphorus bond.
d Figure 4.-Projection
d of the contents of the unit cell onto the ac plane.
Cation Geometry.-Unlike the phenyl groups which were refined as rigid bodies, atoms of the 4methylpyridinium cation were located individually and refined with anisotropic temperature factors. Probably as a result of the domination of the scattering by the five heavy atoms, the positions of the light atoms are not well defined. Comparison of the cation positional parameters before and after introduction of the anisotropic thermal parameters shows little change and no significant improvement inoprecision. The average bond length in the ring is 1.35A, somewhat shorter than might be expected, and the average bond angle within the ring is 119.9'. The single bond to the methyl carbon is of the length expected (1.54 A). It seems reasonable that the hydrogen-bonding interaction should disturb the cation and anion equally, but the effect on the cation is too small to detect in view of the large standard deviations in the light-atom bond lengths. As mentioned above, the N-H proton was located
RICHARD E. DESIMONE AND
GllLEN
D . STUCKY
from a difference Fourier map and the cation ring protons were put in their predicted positions. Proton parameters were not varied since i t was not expected that they could be sufficiently well defined. The N-H distance of 1.01 Lk is slightly longer than expected for a normal N-H proton but perhaps reasonable considering the hydrogen bonding. Overall Structure.-The most notable aspect of the structure is the strong hydrogen bonding which presumably is the force holding the molecule tvgether in the lattice. The N-Br(2) distance of 3.2 A is quite short and has some interesting implications for nmr contact shift studies of ion pairing in solution (involving, for example, the analogous Co2+or Ni2+complexes). While solid-state and solution structures may not be very similar, especially with respect to distortion of the anion, the fact that the cation can approach the anion so closely along what appears to be a direction of no symmetry clearly points up the difficulty of trying to work from a simple model (i.e.,trigonal or tetragonal) for a quantitative treatment of all put the most favorable cases. We also note that 3.2 A is certainly a short enough distance for direct overlap of nitrogen and bromine orbitals containing unpaired spin and that any dipolar shifts on the cation are likely to be complicated by a direct contact i n t e r a ~ t i o n . ' ~ Electron Spin Resonance.-Examination of the single-crystal electron spin resonance spectra of Co2+ doped into the zinc compound indicates immediately that there is a rather strong rhombic component to the electronic structure. The ratio of the zero-field splitting parameters D and E is such that off -diagonal terms coupling the ground spin doublet to the excited doublet16 are of sufficient magnitude that they cannot be neglected and thus transitions only within the =!= doublet observed in the esr experiment do not by themselves serve to determine either g values or zerofield parameters. Powder spectra support this view and indicate that both D and E terms are t o o large to apply the method of Hempel, Morgan, and Lewis1' for the determination of spin Hamiltonian parameters. No quantitative data are thus reported here. Acknowledgment.-The authors wish to express their appreciation to the Advanced Research Projects Agency for financial and equipment support under Contract SD-131 and to Professor R. S. Drago for helpful discussions. (15) D. G. Brown and R. S . Drago, J . Amev. Chem. Soc., 9 2 , 1871 (1870). (16) A. Carrington and A. D. XcLachlan, "Introduction to Magnetic Resonance," Harper and Row, S e w York, N . Y.. 1967. (17) J. C. Hempel, L. 0. Morgan, and W. B. Lewis, I n o v g . Che?n., 9, 2064(1970).
